Process for preparing 1,1,1-trichloroethane

ABSTRACT

A process for preparing 1,1,1-trichloroethane from ethylene and chlorine by hydrochlorinating the ethylene in the presence of aluminum chloride in a liquid phase reaction zone followed by chlorination of the resulting reaction product and finally by hydrochlorination of the effluent from the chlorinator in the presence of ferric chloride. The principal product of this reaction is 1,1,1-trichloroethane. Numerous by-products and partially chlorinated and unsaturated chlorohydrocarbons are also produced but, in the major part, these are recyclable and produce, upon being recycled to the appropriate step, the precursors of or the desired 1,1,1-trichloroethane product.

CROSS-REFERENCE TO RELATED APPLICATION

The present Application is a continuation-in-part of our previousApplication Ser. No. 462,701 filed Apr. 22, 1974, now abandoned.

BACKGROUND OF THE INVENTION

The hydrochlorination of ethylene in the presence of a Friedel-Craftsmetal halide catalyst is an old and well-known procedure. The artemploys principally ethylene and a substantially high purity hydrogenchloride in a boiling bed reactor. The composition of the boiling bed issubstantially the product of the hydrochlorination. Many of theFriedel-Crafts metal halide catalysts have been suggested and dependingupon the conversion, temperature of reaction, pressure, etc., the entirescope is employed. Aluminum chloride or ferric chloride, however, arethe preferred and most commonly referred-to metal halide Friedel-Craftscatalysts. The principal product of this reaction with ethylene is ethylchloride. It has become common practice to purify the ethyl chloridefrom this reaction prior to its use in preparing any number of morehighly chlorinated materials. Likewise, the thermochlorination of ethylchloride is a well-known process. The temperature, pressure, and theratio of chlorine, with or without catalysts, dictate the product whichis obtained. Many processes are known which integrate a di- andtrichloro- product such as, for example, chlorinating ethyl chloride to1,1-dichloroethane recycling the 1,1-dichloroethane with the ethylchloride feed and producing therefrom 1,1,1-trichloroethane. Severaltechniques have been disclosed for carrying out such a process. Again ineach of these processes, it is normal that the effluent product of thechlorination is separated into the desired product and recycle streams.Some desired product may be recycled as a temperature control, thus achlorination control medium. The hydrochlorination of unsaturatedpartially chlorinated hydrocarbons such as vinyl chloride, vinylidenechloride, cis- and trans-dichloroethylene, are each documented in theprior art. The use of ferric chloride and/or aluminum chloride as themetal halide Friedel-Crafts catalyst for these hydrochlorinations isalso well known. The separation of each of the products of thehydrochlorination of one or more of the unsaturated partiallychlorinated hydrocarbons is a rather lengthy procedure requiring severaldistillations to obtain high purity products. It is evident from theprior art that the skilled technician approaches the preparation ofpolychlorinated ethylenes and ethanes in a stepwise manner preferring toseparate the intermediate products and purify them before employing themin the next step. This procedure necessitates several large pieces ofpurification equipment intermediate to the various steps and oftentimesresults in compounds being present as impurities in the desired productwhich create problems in the next step unless removed by chemical means.

It would therefore be advantageous if there were provided a processwhereby ethylene and chlorine were the two external reactants introducedinto a process and therefrom produce 1,1,1-trichloroethane with aminimum of intermediate separations of reaction products in order toprovide feeds for each of the steps of a multi-step process.

It is therefore an object of the present invention to provide such aprocess.

BRIEF DESCRIPTION OF THE INVENTION

In accordance with the present invention, with particular attention tothe drawing, FIG. 1, ethylene 1 is mixed with hydrogen chloride (15) andfed to a hydrochlorinator A wherein the ethylene is hydrochlorinated toethyl chloride 3. The reaction is conducted in a boiling bed of ethylchloride containing aluminum chloride catalyst dispersed throughout. Theresulting gaseous product (ethyl chloride) stream 3 of this firsthydrochlorination is then admixed with a recycle fraction 20 andchlorine and thermally chlorinated in thermal chlorinator B. The recyclefraction 20, obtained from the separation of products in latter steps,has a boiling point between about 37° C and about 60° C and isprincipally 1,1-dichloroethane. The thermal chlorination is carried outat between about 400° and 550° C. The resulting product stream 5 of thisthermal chlorination is subjected to a liquid quench C wherein thosechlorinated hydrocarbons boiling above about 40° C are converted fromthe gaseous state to the liquid state. The nonliquefied gases 6 of theproduct effluent stream under the quench condition, primarily hydrogenchloride, vinyl chloride and vinylidene chloride, and any unreactedethylene and taken overhead. The liquid 7 resulting from the quench C ofthe product effluent from the thermal chlorinator B is in part used asthe quench liquid and in the greater part is admixed with the vinylchloride, vinylidene chloride and hydrogen chloride and any unreactedethylene overhead fraction from the quench C and the resulting mixture10 introduced into a liquid hydrochlorinator D in which ferric chlorideis the metal halide Friedel-Crafts catalyst. Thus, effectively, theentire effluent from the thermal chlorinator is quenched and passeddirectly to the ferric chloride hydrochlorination reactor D. Thisprocedure eliminates a distillation between steps in the process;however, it increases the severity of the final product purificationstep wherein the 1,2 dichloroethane, produced in the reactions and whichwill now appear as an impurity with the 1,1,1-trichloroethane product,is removed. The purification may consist of a distillation of theproduct stream 11 from the hydrochlorinator D. As illustrated the firstdistillation E separates the lights 14 predominantly hydrogen chloride,and minor proportions of ethylene, vinyl chloride, ethyl chloride andvinylidene chloride. The liquid distilland (bottoms) from thisdistillation E are further distilled at F to separate the 1,1-dichloroethane and the near boiling components cis- and trans-dichloroethylenes,stream 17. The bottoms from this still F are further distilled G toobtain 1,1,1-trichloroethane 18 and a bottoms of higher boilingcomponents 19 ethylene dichloride, trichloroethylene,1,1,2-trichloroethane and unsymmetrical tetrachloroethane.

The cis- and trans-dichloroethylenes, produced in small amounts in thethermal chlorinator, have boiling points such that the cis isomer ispractically impossible to separate from the recycle 1,1-dichloroethaneby distillation. If both isomers or the cis isomer alone are allowed toremain with the recycle 1,1-dichloroethane, they pass through thethermal chlorinator and hydrochlorinator essentially unaffected, therebycontinuously increasing in concentration in the recycle,1,1-dichloroethane.

The efficiency of the thermo chlorinator and the ferric chloridehydrochlorinator are improved if the cis- and trans-dichloroethylenesare maintained at a relatively low level by removal from the recycle1,1-dichloroethane stream 20 prior to its use in the thermalchlorinator. Two procedures are provided for this removal: one consistsof separating out the trans by distillation and allowing the cis to cometo equilibrium with trans at the thermal chlorinator reactiontemperature while in the thermal chlorinator. The other is to coldchlorinate the recycle stream during its return to the thermalchlorinator and convert the cis- and trans-dichloroethylenes into highboiling compounds.

The recycled fraction 14 consists of any ethylene, which has passedthrough the reactions unreacted or which is produced in the thermalchlorination, along with the hydrogen chloride, which has not reacted inthe hydrochlorinator, as well as the ethyl chloride, and small amountsof vinyl chloride and vinylidene chloride. These components are returnedto the process, about one-half of the stream 14 represented by stream 15provides the hydrogen chloride for the hydrochlorination of the ethylenein hydrochlorinator A. The excess hydrogen chloride 16 is withdrawn fromthe process.

In an alternative procedure (see dotted lines FIG. 1) in accordance withthe present invention, the above principal steps are carried out withthe single exception that the liquid 7 resulting from the quench of theproduct effluent from the thermal chlorinator B is in part used as thequench liquid and in the greater part is forwarded to a boiling beddehydrochlorinator H containing a Friedel-Crafts catalyst, particularlyiron chloride, and more particularly about 1000 ppm iron chloride. Thedehydrochlorination reactor is operated at conditions which primarilydehydrochlorinate 1,1,1-trichloroethane to vinylidene chloride, thuspermitting separation of 1,2-dichloroethane from the reaction stream.

The gaseous products 8 resulting from the dehydrochlorination in H,(those boiling below about 60° C.) are admixed with the vinyl chloride,vinylidene chloride and hydrogen chloride and any unreacted ethyleneoverhead fraction stream 6 from the quench tower C and the resultingmixture 10 introduced into a liquid hydrochlorinator D in which ferricchloride is the metal halide Friedel-Crafts catalyst. The high boilingmaterials 9 from H are delivered to a still I to recover the recyclablechlorinated materials, predominantly 1,1-dichloroethane 12 which aremixed with recyclables from product finishing system 17. The remainderof this high boiling material is removed from the process 13 and may becombined with the heavies 19 from the 1,1,1-trichloroethane productstill G and these heavies either separated and/or cracked as appropriateto obtain usable higher polychlorinated hydrocarbons.

It follows that elimination of 1,2-dichloroethane from the processfollowing its formation in the thermal chlorinator B as proposed in thedescription above materially reduces the severity of the purificationsteps to obtain the desired product, 1,1,1-trichloroethane, in a highpurity.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the present invention, about 33.9 pounds ethylene(4.4 pounds of which may be separated as a product of the overallprocess) and about 74.6 pounds of hydrogen chloride is reacted at about50° C and about 35 psig in the presence of aluminum chloride catalyst ina boiling bed hydrochlorinator A producing about 74.9 pounds of ethylchloride and about 30.4 pounds excess hydrogen chloride. This is mixedtogether with about 21.8 pounds ethyl chloride and about 98.9 pounds1,1-dichloroethane obtained as products of the overall reaction. Thismixture is reacted in a thermal chlorination reaction zone B for abouttwo seconds at 475° C and 40 psig with 153.7 pounds chlorine. Theresulting product stream is passed into a liquid bed hydrochlorinatorreactor D operating at 45° C and 35 psig where it is contacted withferric chloride (10.4 pounds in 50.2 pounds of perchloroethylene) toproduce in pounds:

    ______________________________________                                        134.9    HCl (hydrogen chloride)                                              4.39     C.sub.2 H.sub.4 (ethylene)                                           .74      C.sub.2 H.sub.3 Cl (vinyl chloride)                                  21.77    C.sub.2 H.sub.5 Cl (ethyl chloride)                                  .95      1,1-C.sub.2 H.sub.2 Cl.sub.2 (vinylidene chloride)                   2.21     t-C.sub.2 H.sub.2 Cl.sub.2 (trans dichloroethylene)                  102.09   1,1-C.sub.2 H.sub.4 Cl.sub.2 (1,1-dichloroethane)                    5.27     c-C.sub.2 H.sub.2 Cl.sub.2 (cis-dichloroethylene)                    106.49   1,1,1-C.sub.2 H.sub.3 Cl.sub.3 (1,1,1-trichloroethane)               1.57     C.sub.2 HCl.sub.3 (1,1,2-trichloroethylene)                          1.68     1,2-C.sub.2 H.sub.4 Cl.sub.2 (1,1-dichloroethane)                    4.50     1,1,2-C.sub.2 H.sub.3 Cl.sub.3 (1,1,2-trichloroethane)               1.25     1,1,1,2-C.sub.2 H.sub.2 Cl.sub.4 (unsym. tetrachloroethane)          ______________________________________                                    

This product stream is separated in several stills E, F and G to obtainproduct (1,1,1-trichloroethane), recycle streams and heavies, of whichthe latter are removed from the system. The hydrogen chloride, vinylchloride, ethyl chloride, and vinylidene chloride and any unreactedethylene are separated as overhead on a first still E and sent to thealuminum chloride hydrochlorinator A; the 1,1-C₂ H₄ Cl₂, cis-1,2-C₂ H₂Cl₂ and trans-1,2-C₂ H₂ Cl₂ overhead from a second still F are sent tothe thermal chlorination reactor B. To prevent the build-up of cis- andtrans-dichloroethylenes in the reactors, they are chlorinated totetrachloroethane enroute 20 at 25° C, care being taken to exclude lightor other radiation. The 1,1,1-trichloroethane is product 18 from thethird still G and the bottoms 19 from the third still are the heavies.

Further to illustrate the use of the present invention in such amulti-reaction train for producing 1,1,1-trichloroethane from ethyleneand chlorine as the sole feeds as set forth in the drawing (FIG. 1), theoverall feed of ethylene of about 242.8 mols/day and about 499.2mols/day of chlorine to produce about 183.9 mols/day of1,1,1-trichloroethane, about 39.2 mols/day of heavies(1,2-dichloroethane, trichloroethylene, 1,1,2-trichloroethane, andtetrachloroethanes). These latter compounds, the heavies, with about381.7 mols/day of hydrogen chloride are removed from the process. Eachcan be employed in other processes.

To illustrate the use of a dehydrochlorination step (FIG. 1 dottedlines) a liquid such as would be obtained from the quench of a thermalchlorinator effluent (Stream 7, FIG. 1) and anhydrous ferric chloride(FeCl₃) are fed to a 1000 cc vessel fitted with a 30-tray distillationcolumn. The rate of take-off from the top tray of the column is adjustedsuch that the overhead temperature is maintained at about 40° C. Thetemperature of the material remaining in the reboiler ranges between 62°and 78° C.

At the end of 7 hours, the feed pump is shut off and the system allowedto cool. During the 7 hour period, 418 grams of liquid and 0.5 gramsFeCl₃ were fed. The table below shows the quantities of the variouscompounds fed and recovered:

    ______________________________________                                        Component        Grams Fed Grams Recovered                                    ______________________________________                                        Vinyl chloride   2.9       4.4                                                Ethyl Chloride   2.6       4.9                                                Vinylidene Chloride                                                                            30.2      203.7                                              trans-1,2-Dichloroethylene                                                                     6.4       6.7                                                1,1-Dichloroethane                                                                             90.9      87.4                                               1,1,1-Trichloroethane                                                                          227.2     5.8                                                cis-1,2-Dichloroethylene                                                                       11.1      8.3                                                Trichloroethylene                                                                              7.0       4.5                                                1,2-Dichloroethane                                                                             9.9       6.1                                                Perchloroethylene                                                                              1.2       0.7                                                1,1,2-Trichloroethane                                                                          20.8      16.4                                               Tetrachloroethane                                                                              8.4       7.6                                                Hydrogen Chloride                                                                              --        62.0                                               Total            418.6     418.5                                              ______________________________________                                    

From the above, it is obvious that 1,1,1- trichloroethane can beconverted to vinylidene chloride in high yields, thus, simplifying itsseparation from compounds with which it is admixed in the thermalchlorinator reaction product.

The following tables set forth the streams which would be produced basedon the foregoing examples to produce 25 million pounds of1,1,1-trichloroethane in accordance with each of the alternative flowdiagrams of FIG. 1. The numbers set forth in the tables are based oncalculations of steady state operation for all streams. The numericalcolumn headings correspond with the stream numbers of FIG. 1.

The process stream calculations were based on the following assumptions:

1. all distillations produce ideal separation and have no losses.

2. The aluminum chloride hydrochlorinator gives 96% yield to ethylchloride based on both ethylene and hydrogen chloride. It also gives100% conversion of ethylene fed. (A conservative assumption based onactual experience).

3. The thermal chlorinator gives 100% conversion of chlorine fed and hasthe product distribution similar to that obtained in the laboratory.

4. Quench system is operated such that all 1,1,1-trichloroethane remainsin the liquid phase of the quench.

5. The ferric chloride dehydrochlorinator gives 97% conversion of1,1,1-trichloroethane present in the thermal chlorinator product tovinylidene chloride. Other components are unaffected.

6. The ferric chloride hydrochlorinator gives:

98% conversion of vinyl chloride to 1,1-dichloroethane

56% conversion of ethylene to ethyl chloride

96% conversion of vinylidene chloride to 1,1,1-trichloroethane Othercomponents are unaffected.

7. Chlorination of 1,1-dichloroethane recycle stream gives 100%conversion of cis and trans-1,2-dichloroethylene to tetrachloroethanewith 2% loss of 1,1-dichloroethane to 1,1,2-trichloroethane.

8. Compression and separation of recycle HCl and lights are ideal withno loss.

    __________________________________________________________________________    1,1,1-TRICHLOROETHANE PROCESS WITHOUT DEHYDROCHLORINATION STEP                Based on Process Producing 25 -- M Lbs./Year 1,1,1-Trichloroethane            Numbers are in Lb. Moles Per Year                                                          1     2    3     4    5                                          __________________________________________________________________________    Chlorine                      508,561.8                                       Ethylene     247,367.6                                                                           284,133.3       83,559.8                                   Hydrogen Chloride  479,733.9                                                                          195,600.7                                                                           195,600.7                                                                          1,106,266.7                                Vinyl Chloride     2,778.8         138,938.6                                  Ethyl Chloride     79,311.4                                                                           352,081.2                                                                           352,081.2                                                                          32,517.3                                   Vinylidene Chloride                                                                              2,282.0         57,050.2                                   trans-Dichloroethylene             5,340.2                                    1,1-Dichloroethane            234,720.8                                                                          103,347.5                                  cis-Dichloroethylene               12,786.5                                   1,1,1-Trichloroethane              103,328.0                                  Ethylene Dichloride                4,005.2                                    Trichloroethylene                  2,815.0                                    1,1,2-Trichloroethane         4,910.7                                                                            13,360.9                                   unsymm-tetrachloroethane      18,126.7                                                                           19,699.8                                   __________________________________________________________________________                 6     7    10    11   14                                         __________________________________________________________________________    Chlorine                                                                      Ethylene     82,799.1                                                                            760.7                                                                              83,559.8                                                                            36,765.7                                                                           36,765.7                                   Hydrogen Chloride                                                                          1,082,753.2                                                                         23,513.5                                                                           1,106,266.7                                                                         868,513.6                                                                          868,513.6                                  Vinyl Chloride                                                                             122,348.8                                                                           16,589.8                                                                           138,938.6                                                                           2,778.8                                                                            2,778.8                                    Ethyl Chloride                                                                             29,453.9                                                                            3,063.4                                                                            32,517.3                                                                            79,311.4                                                                           79,311.4                                   Vinylidene Chloride                                                                        33,034.8                                                                            24,015.4                                                                           57,050.2                                                                            2,282.0                                                                            2,282.0                                    trans-Dichloroethylene                                                                     2,147.5                                                                             3,192.7                                                                            5,340.2                                                                             5,340.2                                         1,1-Dichloroethane                                                                         27,513.5                                                                            75,834.0                                                                           103,347.5                                                                           239,507.1                                       cis-Dichloroethylene                                                                       3,430.8                                                                             9,355.7                                                                            12,786.5                                                                            12,786.5                                        1,1,1-Trichloroethane                                                                            130,328.0                                                                          130,328.0                                                                           187,378.2                                       Ethylene Dichloride                                                                              4,005.2                                                                            4,005.2                                                                             4,005.2                                         Trichloroethylene  2,815.0                                                                            2,815.0                                                                             2,815.0                                         1,1,2-Trichloroethane                                                                            13,360.9                                                                           13,360.9                                                                            13,360.9                                        unsymm-tetrachloroethane                                                                         19,699.8                                                                           19,699.8                                                                            19,699.8                                        __________________________________________________________________________                 15    16   17    18   19    20                                   __________________________________________________________________________    Chlorine     36,765.7                                                         Ethylene                                                                      Hydrogen Chloride                                                                          479,733.9                                                                           388,810.7                                                  Vinyl Chloride                                                                             2,778.8                                                          Ethyl Chloride                                                                             79,311.4                                                         Vinylidene Chloride                                                                        2,282.0                                                          trans-Dichloroethylene  5,340.2                                               1,1-Dichloroethane      239,507.1        234,720.8                            cis-Dichloroethylene    12,786.5                                              1,1,1-Trichloroethane         187,378.2                                       Ethylene Dichloride                4,005.2                                    Trichloroethylene                  2,815.0                                    1,1,2-Trichloroethane              13,360.9                                                                            4,910.7                              unsymm-tetrachloroethane           19,699.8                                                                            18,126.7                             __________________________________________________________________________    1,1,1-TRICHLOROETHANE PROCESS INCLUDING DEHYDROCHLORINATION STEP              Based on Process Producing 25 -- M Lbs./Year 1,1,1-Trichloroethane            Numbers are in Lb. Moles Per Year                                                          1     2    3     4    5                                          __________________________________________________________________________    Chlorine                      530,676                                         Ethylene     258,124                                                                             296,489         87,193.3                                   Hydrogen Chloride  500,595                                                                            204,106                                                                             204,106                                                                            1,154,372                                  Vinyl Chloride     2,899.6         144,980                                    Ethyl Chloride     82,760.2                                                                           367,391                                                                             367,391                                                                            33,931.3                                   Vinylidene Chloride                                                                              7,656.7         59,531.0                                   trans-Dichloroethylene             5,572.4                                    1,1-Dichloroethane            244,820                                                                            107,842                                    cis-Dichloroethylene               13,342.5                                   1,1,1-Trichloroethane              136,006                                    Ethylene Dichloride                4,179.3                                    Trichloroethylene                  2,937.4                                    1,1,2-Trichloroethane         5,124.3                                                                            13,941.9                                   unsymm-tetrachloroethane      18,914.9                                                                           20,556.4                                   __________________________________________________________________________                 6     7    8     9    10                                         __________________________________________________________________________    Chlorine                                                                      Ethylene     86,399.6                                                                            793.75                                                                             793.75     87,193.3                                   Hydrogen Chloride                                                                          1,129,836                                                                           24,536.0                                                                           156,460    1,286,296                                  Vinyl Chloride                                                                             127,669                                                                             17,311.2                                                                           17,311.2   144,980                                    Ethyl Chloride                                                                             30.734.7                                                                            3,196.6                                                                            3,196.6    33,931.3                                   Vinylidene Chloride                                                                        34,471.3                                                                            25,059.7                                                                           156,984    191,455                                    trans-Dichloroethylene                                                                     2,240.9                                                                             3,331.6    3,331.6                                                                            2,240.9                                    1,1-Dichloroethane                                                                         28,709.9                                                                            79,131.7   79,131.7                                                                           28,709.9                                   cis-Dichloroethylene                                                                       3,580.0                                                                             9,762.5    9,762.5                                                                            3,580.0                                    1,1,1-Trichloroethane                                                                            136,006    4,082.1                                         Ethylene Dichloride                                                                              4,179.3    4,179.3                                         Trichloroethylene  2,937.4    2,937.4                                         1,1,2-Trichloroethane                                                                            13,941.9   13,941.9                                        unsymm-tetrachloroethane                                                                         20,556.4   20,556.4                                        __________________________________________________________________________                 11    12   13    14   15                                         __________________________________________________________________________    Chlorine                                                                      Ethylene     38,364.4         38,364.4                                                                           38,364.4                                   Hydrogen Chloride                                                                          911,588          911,588                                                                            500,595                                    Vinyl Chloride                                                                             2,899.6          2,899.6                                                                            2,899.6                                    Ethyl Chloride                                                                             82,760.2         82,760.2                                                                           82,760.2                                   Vinylidene Chloride                                                                        7,656.7          7,656.7                                                                            7,656.7                                    trans-Dichloroethylene                                                                     2,240.9                                                                             3,331.6                                                    1,1-Dichloroethane                                                                         170,791                                                                             79,131.7                                                   cis-Dichloroethylene                                                                       3,580.0                                                                             9,762.5                                                    1,1,1-Trichloroethane                                                                      187,378    4,082.1                                               Ethylene Dichloride     4,179.3                                               Trichloroethylene       2,937.4                                               1,1,2-Trichloroethane   13,941.9                                              unsymm-tetrachloroethane                                                                              20,556.4                                              __________________________________________________________________________                 16    17   18    20                                              __________________________________________________________________________    Chlorine                                                                      Ethylene                                                                      Hydrogen Chloride                                                                          410,993                                                          Vinyl Chloride                                                                Ethyl Chloride                                                                Vinylidene Chloride                                                           trans-Dichloroethylene                                                                           2,240.9                                                    1,1-Dichloroethane 170,791    244,820                                         cis-Dichloroethylene                                                                             3,580.0                                                    1,1,1-Trichloroethane   187,378                                               Ethylene Dichloride                                                           Trichloroethylene                                                             1,1,2-Trichloroethane         5,124.3                                         unsymm-tetrachloroethane      18,914.9                                        __________________________________________________________________________

What is claimed is:
 1. A method for preparing 1,1,1-trichloroethanewhich comprises:1. reacting ethylene, recycle ethylene from a later stepin the process and hydrogen chloride, said hydrogen chloride beingobtained from another step in the process, together in a liquid boilingreaction medium in the presence of a Fridel-Crafts aluminum chloride(AlCl₃) catalyst thereby to produce predominantly ethyl chloride; 2.reacting in the gas phase in a thermal reactor the so-produced ethylchloride, recycle ethyl chloride from a later step and recycle1,1-dichloroethane stream from another step in the process with chlorineat a temperature of from 400° to b 550° C;
 3. subjecting the so-producedreaction mixture from the thermal chlorination Step (2) to ahydrochlorination reaction in a liquid reaction medium in the presenceof a Friedel-Crafts ferric chloride (FeCl₃) catalyst to convertvinylidene chloride in the said so-produced thermal chlorinationreaction mixture to 1,1,1-trichloroethane and vinyl chloride in saidso-produced thermal chlorination reaction mixture to1,1-dichloroethane;4. separating the hydrochlorination reaction mixturefrom Step (3) by distillation to recover a) 1,1,1-trichloroethane, asproduct, b) a lights fraction predominantly comprised of ethylene, ethylchloride, and hydrogen chloride for recycling to Step (1), and c) arecycle fraction boiling between about 37° and about 60° C atatmospheric pressure which is principally 1,1-dichloroethane for recycleto Step (2).
 2. A method for preparing 1,1,1-trichloroethane whichcomprises:1. reacting ethylene, recycle ethylene from a later step inthe process and hydrogen chloride, said hydrogen chloride being obtainedfrom another step in the process, together in a boiling liquid reactionmedium in the presence of a Friedel-Crafts aluminum chloride (AlCl₃)catalyst thereby to produce predominantly ethyl chloride;
 2. reacting inthe gas phase in a thermal reactor the so-produced ethyl chloride,recycle ethyl chloride from a latter step and a predominantly1,1-dichloroethane stream from another step in the process with chlorineat a temperature of from 400° to 550° C;3. subjecting the so-producedreaction mixture from the thermal chlorination Step (2) to a quenchstep, separating the quenched thermal chlorination reaction mixture intoa fraction boiling below about 40° C and a fraction boiling above about40° C;
 4. subjecting the fraction from step (3) boiling above about 40°C to dehydrochlorination in a boiling liquid reaction medium in thepresence of a Friedel-Crafts ferric chloride (FeCl₃) catalyst to convertthe 1,1,1-trichloroethane therein to vinylidene chloride;5. separatingthe dehydrochlorination reaction mixture from Step (4) into a fractionboiling below about 60° C predominantly comprised of vinylidenechlorideand into a fraction boiling above about 60° C;
 6. combining the fractionboiling below about 60° C from Step 5 with the fraction boiling belowabout 40° C from Step 3 and subjecting the resultant mixture tohydrochlorination in a liquid reaction medium in the presence of aFriedel-Crafts ferric chloride (FeCl₃) catalyst to convert vinylidenechloride therein to 1,1,1-trichloroethane and vinyl chloride therein to1,1-dichloroethane;
 7. separating the hydrochlorination reaction mixturefrom Step (6) by distillation to recover a) 1,1,1-trichloroethane, asproduct, b) a lights fraction predominantly comprised of ethylene, ethylchloride and hydrogen chloride for recycling to Step (1), and c) arecycle fraction boiling between about 37° and about 60° C atatmospheric pressure which is principally 1,1-dichloroethane for recycleto Step (2).
 8. subjecting the fraction boiling above about 60° C fromStep (5) to a distillation to recover recyclable chlorinated materialscomprised predominantly of 1,1-dichloroethane for recycle to Step (2).3. A method for preparing 1,1,1-trichloroethane which comprises:1.reacting ethylene, recycle ethylene from a later step in the process andhydrogen chloride, said hydrogen chloride being obtained from anotherstep in the process, together in a boiling liquid reaction medium in thepresence of a Friedel-Crafts aluminum chloride (AlCl₃) catalyst therebyto produce predominantly ethyl chloride;
 2. reacting in the gas phase ina thermal reactor the so-produced ethyl chloride, recycle ethyl chloridefrom a later step and a predominantly 1,1-dichloroethane stream from alater step in the process with chlorine at a temperature of from 400° to550° C;
 3. subjecting the so-produced reaction mixture from the thermalchlorination Step (2) to hydrochlorination in a liquid reaction mediumin the presence of a Friedel-Crafts ferric chloride (FeCl₃) catalyst toconvert vinylidene chloride in the said so-produced thermal chlorinationreaction mixture to 1,1,1-trichloroethane and vinyl chloride in saidso-produced thermal chlorination reaction mixture to 1,1-dichloroethane;4.
 4. separating the hydrochlorination reaction mixture from Step (3) bydistillation to recover a). 1,1,1-trichloroethane, as product, b). alights fraction predominantly comprised of ethylene, ethyl chloride andhydrogen chloride for recycling to Step (1), c). a fraction boilingbetween about 37° and about 60° C at atmospheric pressure which isprincipally 1,1-dichloroethane and cis and trans 1,2-dichloroethylenes;and d). a fraction consisting essentially of higher boilingpolychlorinated ethanes including tetrachloroethanes;5. chlorinating the1,1-dichloroethane containing fraction from Step (4) c) in the dark inthe absence of catalyst to chlorinate the cis- andtrans-1,2-dichloroethylene to tetrachloroethane; b. recycling theso-produced chlorination reaction mixture from Step (5) to Step (2). 4.A method for preparing 1,1,1-trichloroethane which comprises:1. reactingethylene, recycle ethylene from a later step in the process and hydrogenchloride, said hydrogen chloride being obtained from another step in theprocess, together in a boiling liquid reaction medium in the presence ofa Friedel-Crafts aluminum chloride (AlCl₃) catalyst thereby to producepredominantly ethyl chloride;
 2. reacting in the gas phase in a thermalreactor the so-produced ethyl chloride, recycle ethyl chloride from alater step and a predominantly 1,1-dichloroethane stream from anotherstep in the process with chlorine at a temperature of from 400° to to550° C;3. subjecting the so-produced reaction mixture from the thermalchlorination Step (2) to a quench step, separating the quenched thermalchlorination reaction mixture into a) a fraction boiling below about 40°C and b) a fraction boiling above about 40° C;
 4. subjecting thefraction from Step (3) boiling above about 40° C to dehydrochlorinationin a boiling reaction medium in the presence of a Friedel-Crafts ferricchloride (FeCl₃) catalyst to convert the 1,1,1-trichloroethane thereinto vinylidene chloride;
 5. separating the dehydrochlorination reactionmixture from Step (4) into a fraction boiling below about 60° Cpredominantly comprised of vinylidene chloride and into a fractionboiling above about 60° C;
 6. combining the fraction boiling below about60° C from Step (5) with the fraction boiling below about 40° C fromStep 4 and subjecting the resultant mixture to hydrochlorination in aliquid reaction medium in the presence of a Friedel-Crafts ferricchloride (FeCl₃) catalyst to convert vinylidene chloride therein to1,1,1-trichloroethane and vinyl chloride therein to1,1-dichloroethane;7. separating the hydrochlorination reaction mixturefrom Step (6) by distillation to recover a) 1,1,1-trichloroethane, asproduct, b) a lights fraction predominantly comprised of ethylene, ethylchloride and hydrogen chloride for recycling to Step (1), and c) afraction boiling between about 37° and about 60° C at atmosphericpressure which is principally 1,1-dichloroethane and cis- andtrans-1,2-dichloroethylene;
 8. subjecting the fraction boiling aboveabout 60° C from Step (5) to a distillation to recover recyclablechlorinated materials comprised predominantly of 1,1-dichloroethane andcis- and trans-1,2-dichloroethylene;
 9. combining the fraction obtainedfrom Step (7) (c) and the recyclable chlorinated materials obtained bydistillation in Step (8) and subjecting the resultant mixture comprisedpredominantly of 1,1-dichloroethane and cis- andtrans-1,2-dichloroethylene to a distillation to remove thetrans-1,2-dichloroethylene from said resultant mixture and recovering afraction comprised predominantly of 1,1-dichloroethane andcis-1,2-dichloroethylene;
 10. recycling the fraction comprisedpredominantly of 1,1-dichloroethane and cis-1,2-dichloroethylene fromStep (9) to the thermal gas phase chlorination Step (2) wherein saidcis-1,2-dichloroethylene will isomerize to an equilibrium mixture ofcis-trans forms of 1,2-dichloroethylenes which will eventually besubjected to distillation Step (9) to remove the trans form so formedand thereby to prevent build-up of the 1,2-dichloroethylenes in therecycle.